diff options
| author | Emil Velikov <emil.l.velikov@gmail.com> | 2020-05-05 17:03:27 +0100 |
|---|---|---|
| committer | Sam Ravnborg <sam@ravnborg.org> | 2020-06-29 09:40:41 +0200 |
| commit | e192fba23ef5ed1439fe699d808c480ca969b0ed (patch) | |
| tree | 1bbf9cb34681c89e9232ebe8779fdc56934b09a6 | |
| parent | 8767c3fc28b2c34170cac2b0691a0f045401e31f (diff) | |
drm/dsi: use stack buffer in mipi_dsi_dcs_write()
Currently the function heap allocates when we have any payload. Where in
many case the payload is 1 byte - ouch.
>From casual observation, vast majority of the payloads are smaller than
8 bytes - so use a stack array tx[8] to avoid the senseless kmalloc and
kfree dance.
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Thierry Reding <treding@nvidia.com>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200505160329.2976059-1-emil.l.velikov@gmail.com
| -rw-r--r-- | drivers/gpu/drm/drm_mipi_dsi.c | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c index 55531895dde6..b96d5b4629d7 100644 --- a/drivers/gpu/drm/drm_mipi_dsi.c +++ b/drivers/gpu/drm/drm_mipi_dsi.c @@ -748,26 +748,26 @@ ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, u8 cmd, { ssize_t err; size_t size; + u8 stack_tx[8]; u8 *tx; - if (len > 0) { - size = 1 + len; - + size = 1 + len; + if (len > ARRAY_SIZE(stack_tx) - 1) { tx = kmalloc(size, GFP_KERNEL); if (!tx) return -ENOMEM; - - /* concatenate the DCS command byte and the payload */ - tx[0] = cmd; - memcpy(&tx[1], data, len); } else { - tx = &cmd; - size = 1; + tx = stack_tx; } + /* concatenate the DCS command byte and the payload */ + tx[0] = cmd; + if (data) + memcpy(&tx[1], data, len); + err = mipi_dsi_dcs_write_buffer(dsi, tx, size); - if (len > 0) + if (tx != stack_tx) kfree(tx); return err; |